In a semiconductor apparatus which is used for an electronic apparatus such as an electronic computer, the degree of integration of circuits has increased to a high level, so that the quantity of heat generated at the semiconductor apparatus has greatly increased. The semiconductor apparatus for use in a large-scale computer has been adapted a module structure which packages a plurality of semiconductor elements thereinto in order to reduce the length of the electric lines between each element and increase calculating speed of the large-scale computer. Removal of the heat generated during the operation of the large-scale computer is indispensable serious problem for maintaining stable operation performance thereof.
In general, a cooling system has been employed wherein the module mounting a plurality of semiconductor elements absorbs the heat generated from the semiconductor elements a cooling medium flow, for example, water through a cooling jacket attached to the module. A system of the aforementioned type is disclosed, for example in FIG. 5 of WO 89/12319, published Dec. 14, 1989 entitled "Semiconductor Packing Module and Heat Conducting Block Structure Used Therefore". In this system cooling water enters into a protrusion with a triangular cross section of the heat-conducting block and flows near the semiconductor elements.
Further, a cooling system has been proposed in, for example, U.S. Pat. No. 4,193,445, wherein the heat generated from the semiconductor elements mounted on a substrate is conducted to the cooling medium enclosed in the cooling jacket through the piston-type cooling elements which contact to the semiconductor elements and move slidably into the thermal conductor. The cooling elements mentioned contact to the pistons through compression springs, respectively, for performing sufficient heat conduction of heat generated from the semiconductor elements.
According to the heat-conducting block shown in FIG. 5 of WO 89/12319, the fin is required for flowing the cooling water to the cooling fin mounted on the lower heat conductive block. The outlet for flowing the cooling medium is required between the cooling fine and the lower heat conductive block. The structure shown in WO 89/12319 is complex and the cooling effect thereof is not always sufficient.
In the cooling system which comprises the thermal conductor and the cooling jacket as proposed in U.S. Pat. No. 4,193,445, the thermal resistance of the contacting portions, between the thermal conductor and the cooling jacket creates a problem which disturbs the thermal conductivity. The thermal conductor and the cooling jacket are fixed by a threaded connection, and the substrate mounting the thermal conductor or the semiconductor elements may be deformed or broken due to unbalance of stress caused by fixing of the thermal conductor and the cooling jacket, or thermal stress caused by the difference of the coefficients of the thermal expansion of the thermal conductor and the cooling jacket.
In general, a ceramic thermal conductor and a copper cooling jacket have been used taking into consideration the electrical insulation, thermal conductivity and manufacturing thereof. Since the coefficients of thermal expansion of the ceramic thermal conductor and the copper cooling jacket are different, respectively, thermal stress is generated when they go through heat cycle so that they are broken.